Projectors are widely used in schools, trade shows, businesses, museums, and anywhere that a screen is needed to be shown on a large surface. A projector may be coupled to a computer, and may then project computer displays onto a screen. The user is frequently standing near the screen, and not near the computer. Thus, it is difficult to coordinate the computer's operation. An external device may be used, e.g., to progress through slides in a presentation. However, external devices are frequently confusing and of limited utility. It would be advantageous for a system to allow a user to have increased interaction with a projection system.